Antenna mast



April16,1946. 'l J. R..AMPBEL| 2,398,357 ANTENNA MAST Filed Jan. 19,1944 ATTORNEY Patented Apr. 16, 1946 ANTENNA MAST James R. Campbell,Columbus, Ohio, assignor to Curtiss-Wright Corporation, a corporation ofDelaware Application January 19, 1944, serial No. 519,081

7 Claims.

This invention relates to antenna masts which are adapted especially,although not necessarily, for use in connection with aircraft, beingconcerned more particularly with a collapsible antenna mast which may bereleasably secured in Aits elevated position and which may be loweredvwhen the aircraft by which it is carried is to be handled by a hoistingsling, or similar apparatus, in order to thereby avoid, in so far aspossible, damage to the mast, the antenna, or that portion of theaircraft by which the mast is supported.

, One object of the invention is to provide an antenna mast of thecharacter generally described which may be securely locked againstvibration in its elevated position and wherein pro` vision is made forfacilitating the release of the mast when it is tov be lowered orcollapsed,

A further object is to provide a mast wherein the mechanism which isemployed to releasably secure the mast in its elevated position, ishoused in such a manner that it is well protected from the elements andmay be readily actuated from the exterior of the aircraft by which it iscarried.

A still further object is a novel design and arrangement of the parts ofthe mast, whereby to provide compensation for Wear and obtain simplicityin construction and dependability in operation.

The invention is illustrated in the accompanying drawing, in which:

Figure 1 is a perspective view of an airplane carrying an antenna mastembodying the features of the invention, a hoisting sling being shownattached to the airplane in a conventional manner.

Figure 2 is an enlarged side view, partially in elevation and partiallyin section, of the antenna mast. Y

Figure 3 is a horizontal section through the mast taken along line 3 3of Figure 2.

Figure 4 is a vertical section taken along line 4-4 of Figure 2.

Figure 5 is a horizontal section taken along line 5 5 of the samefgure.

Figure 6 is a fragmentary, vertical section` taken along line 6 -6 ofFigure 2.

The antenna mast, indicated at 9, is illustrated by way of example inconnection with an airplane I of the type designed to arise from andalight on water. 'I'he cockpit of the airplane shown is enclosed by awindshield II, which is xed to the fuselage I2, and a sliding hatch I3,the latter fitting against the windshield when closed and, in accordancewith conventional practice, being movable rearwardly to provide accessto the cockpit. A base member I4 of the mast is mounted at the top ofthe windshield, preferably so that the mast is supported in the plane ofsymmetry of the airplane. An antenna I is connected at one end by aninsulator I6 and spring -I'I to the upper end of the mast and isconnected at its opposite end by an insulator I8 to the leading edge ofa vertical n I9. Ahoisting sling for lifting the airplane from thesurface of the water on which it may rest is suciently indicated for thepurpose in View by a showing of the lower end thereof, it being thepractice to attach the sling to the fuselage close to the center ofgravity of the airplane so that the latter will, as illustrated,normally assume a y substantiallyfhorizontal position. However, beingexposed to air currents, the airplane may, while being hoisted, becaused to pivot forwardly or rearwardly about the points 2| at which`the sling is attached to the fuselage. In the event that the airplaneshould pivot forwardly there is a real possibility that the mast willengage or become entangled with the sling, with resultant damage to themast, the windshield to which the fast is attached or the antenna. s Inorder to avoid this possibility the mast is designed so that it may belowered to the dotted-line'position indicated in Figure 1. When the mastis lowered to such position, the airplane may swing about the attachmentpoints 2| through a wide range of movement without danger ofinterference between the mast and the hoisting sling when the airplaneis being handled as an incident to its storage aboard a water-born craftor for other purposes.

As illustrated, the base member I 4 seats against a transparent panel ofthe windshield and is formed with attaching flanges to facilitate itsmounting upon said panel and the framework of the windshield. Anelevatedportion 22 on the base member I 4 is formed with a transverselyextending tongue 23 to which the lower end of the mast is pivotallyconnected by acouplingv member 24. The upper end of the latter issuitably secured in the lower end of the hollow body` of the mast whilelegs 25 at the lower end of the coupling member straddle the tongue 23and are pivotally connected thereto by a pin 26, the end of the tongue23 and the ends of the legs 25 being arcuate and being accommodated inconforming recesses formed in the coupling and base members.Preferably'the mast with respect to its cross section, and including theelevated portion 22 of the base member, is of streamline form,

the upper end of the mast carrying an ear 21 for supporting the leadingend of the antenna. The

pin 26 may, as illustrated in Figure 3, be formed with a bore 28 and aport 29 through which lubricant introduced into the pin through a tting30 may escape to ubricate the exterior surface of the pin and theinterior surface of a bushing 3l in which the central portion of the pinis accommodated, as well as lubricating the contacting surfaces of thetongue 23 and legs 25, Preferably the bushing 3lv is pressed into thetongue 23 so that it will be held against rotation, the pin 26 beingsecured against axial displacement by a setscrew 32 which is carried bythe rear leg of the coupling member and the inner end of which isaccommodated in a circumferential groove 33 formed in the outer end ofthe pin. As the set. screw engages the pin in the groove 33, it will notmar or otherwise damage the bearing surface of the pin in such a mannerthat the latter willscore the bearing surface of the rear leg when it isremoved. In order to facilitate removal of the pin when it is desired todismount the mast, an access aperture 34 is formed in the front leg ofthe coupling member 24. Hence whenv the set screw 32 is sufficientlyloosened and the tting 30V is removed, a tool may be inserted throughthe said aperture to engage the pin and expel it.

The base member is adapted to support the mast either inan elevated orin a collapsed, or lowered, position,rthe mast in the latter positionbeing substantially horizontal and occupying a plane which issubstantially normal with respect to the plane which it occupies whenelevated. In order te avoid an increase in the tension of the antenna lwhich would otherwise occur when the mast is lowered and at the sametime preferably reduce such tension, the pin 26 is so mounted that asthe mast is lowered the outer end thereof is swung slightly in thedirection of the tail fin I9. By mounting the pin 26 at an angle of 7%degrees with respect -to the transverse major axis of the mast, asindicated in Figure 3, the distance between the attachment ear 21 andthe point of attachment of the antenna with the tail fin I9 will bereduced as the mast is lowered. The tension upon the antenna will,therefore, be correspondingly lessened, it being understood in thisconnection that the plane which the pin 26 occupies is substantiallynormal with respect to the longitudinal axis of the mast when the latteris elevated.

In order to limit the angular movement of the mast upon the pin 26, theforward leg 25 of the coupling member is formed with a shoulder 35(Figure 6) which engages a stop portion 36 on the base member as themast, moving from a lowered position, reaches its normal elevatedposition, When the mast is moved from an elevated to a lowered position,the opposite side of the rear leg 25 of the coupling member engages astop portion 31 on the base member to arrest the mast when the latterreaches a substantially horizontal position.

The mast is locked in itsA elevated position by a plunger-like detent 38which is carried by a stem 39, the detent being formed with a taperedend which is adapted to be accommodated in a socket 46 formed in thetongue 23. The detent has a relatively close sliding lit in the lowerend of a bore 4I in the coupling member and the tapered end extendsbetween the legs 25 of the coupling member. The bore 4l which terminatesshort of an arched top wall 42 of the coupling member accommodates thestern 39 and a spring 43 which acts against the detent to bias it towardan extended, or locking, position. The detent may be adequatelylubricated by a suitable medium which may be introduced into a duct 44.

A forked inner end of a lever 45 is pivotally connected by a pin 46 tothe upper end of the stem 39, the legs 41 of the forked end of the leverbeing formed to provide cams 48 which are engageable with the arched topwall 42 of the coupling member to initiate vwithdrawal of the detent 38.Aspring 49 which isformed with companion loops, one of which is locatedat either side of the stem 39, is connected at its ends to the oppositeends of a cross-pin 50 which is carried by a shoulder 5| on the top wallof the coupling member 24, the spring 49, at the juncture oi its twoloops, engaging the lever 45 normally to hold it in an upper, orretracted, position, as indicated in full lines in Figure 2. When heldin this position the cams 48 on the lower end of the lever 45 aresupported above and out of Contact with the top wall of the couplingmember. The cooperating tapered walls of the detent and socket and thespacing of the cams. 48 above the top wall of the coupling member insurelocking of the mast in itsv elevated position so that it will be heldagainst vibration. At the same time provision is made for compensatingfor wearing of the parts. Except for the outer end of the actuatinglever 45the parts of the locking mechanism described are wholly enclosedwithin the mast, the hollow body of the latter being formed with anelongated opening 52 in which a collar 53 is suitably secured and beingextended rearwardly in this area. The side walls of the lcollar providea guideway for the free end of the lever while the two end walls denethe two limits of its range of movement.

When it is desired to release the detent 38Yso that the mast may belowered, it is only necessary to actuate the lever45. As the latter isswung downwardly the cams 43 act upon the top wall of the couplingmember to thereby initiate withdrawal ofthe detent from its socket inthe said wall. By virtue of theuse of the airplane under conditionswhich, at times, promote the accumulation of moisture on the parts ofthe locking mechanism, there may be a tendency, which is aggravatedbythe` shape of the intertting parts, for the said parts to seize.However, owing to the high mechanical advantage obtained by the cams 48,freeing of the detent in its socket may be readily effected despite suchtendency. Thereafter, of course, a highl mechanical advantage is notrequired. Hence, after the detent is freed and as the lever is movedfurther in the same direction, the lever engages and pivots about theshoulder 5|, utilizing the latter as a fulcrum during its movement fromthe intermediate, dot-tedline position shown in Figure 2 to thelowermost, dotted-line position. In other words during the initial partof its movement the cams give the lever a high enough mechanicaladvantage to insure freeing of the detent in its socket. Thereafter thefulcrum which is provided by the shoulder 5I effects a substantialincrease in the travel of the detent, thereby completing withdrawal ofthe detent from the socket. Upon release of the detent the mas-t may bereadily lowered, this loe-y ing aided by gravity and the action of thespring Il. When the mast is again elevated it is unnecessary tomanipulate the lever 45. The detent which is held extended by the spring43 to a posiltion determined by the cams 48 will engage and ride over arounded edge portion 54 on the tongue 23, the spring 43 causing theplunger to enter the socket 4.6 and lock the parts against furtherrelative movement when the mast reaches an upright position.

I claim as my invention:

1. A collapsible antenna mast including a base member, a stail pivotallymounted on said base member and movable to elevated and loweredpositions, a detent, resilient means for biasing said detent to locksaid staff in said elevated position, a lever pivotally connected tosaid detent, resilient means for normally holding said lever in aretracted position, and a fulcrum about which said lever may pivotagainst the action of both of said resilient means to transmit a portionof its movement to said detent to thereby release said staff so that itmay be lowered.

2. A collapsible antenna mast including a base member, a stai pivotallymounted on said base member and movable to elevated and loweredpositions, a detent, resilient means for biasing said detent to locksaid staff in said elevated position, a lever pivotally connected tosaid detent, resilient means for normally holding said lever in aretracted position, and means against which said lever acts to transmita portion of its movement to said detent against the resistance oieredby both of said resilient means to thereby release said staff so that itmay be lowered, said lever being spaced from said last named means whenheld in said retracted position in the manner described.

3. A collapsible antenna mast including a base member, a staff pivotallymounted on said base y member and movable to elevated and loweredpositions, a detent for locking said staff in said elevated position, alever having a pivotal con` nection with said detent, and means withwhich end and intermediate portions of said lever are successivelyengageable when the latter is actuated thereby to rst free said detentand thereafter move it to a fully released position so that said staimay be lowered.

4. A collapsible antenna mast including a base member, a staff pivotallymounted on said base member and movable to elevated and loweredpositions, a detent for locking said staff in said elevated position, alever havingpa pivotal connection with said detent, means for normallyholding said lever iny a retracted position, means which the end of saidlever initially engages when the latter is actuated to free said detent,and a fulcrum about which said lever thereafter pivots to complete themovement of said detent to a fully released position.

5. A'collapsble antenna mast including a base member, a stai pivotallymounted on said base member and movable to elevated and loweredpositions, a detent, a lever having a pivotal connection with saiddetent, means for normally holding said lever in a retracted position,means for providing a socket which said detent may enter with a wedgingaction to lock said staff against vibration in said elevated position,means which the end of said lever initially engages when said lever isactuated to free said detent in `said socket, and a fulcrum about whichsaid lever thereafter pivots to complete the movement of said detent toa fully released position.

6. A collapsible antenna mast including a base Y member, a staffpivotally mounted on said base member and movable to elevated andlowered positions, a detent, a lever having a pivotal connection withsaid detent, means for normally holding said lever in a retractedposition, means "for providing a socket which said detent may enter,resilient means for causing said detent to engage the walls of saidsocket with a wedging action to lock said stai against vibration in saidelevated position, `means which the end of said lever initially engageswhen said lever is actuated to free said detent in said socket, and afulcrum about which said lever thereafter pivots to complete themovement of said detent to a fully released position.

7. A collapsible antenna mast including a base member, a staff pivotallymounted on said base member and movable to elevated and loweredpositions, a detent, a lever having a pivotal connection with saiddetent, means for normally holding said lever in a retracted position,means for providing a socket which said detent may enter, resilientmeans for causing said detent to engage the walls of said socket with awedging action to lock said staff against vibration in said elevatedposition, means which the end of said lever initially engages when saidlever is actuated to free said detent in said socket, and a fulcrumabout which said lever thereafter pivots to complete the movement ofsaid detent to a fully released position, the end of said lever beingspaced from said last named means when said lever occupies saidretracted position.

JAMES R. CAMPBELL.

